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Full text of "Text Book Of Mechanical Engineering"

IO4                       Forging Bolt and Nut.

the tongs %and struck t>n the anvil as at B. A heading tool is next
held over a hole in the anvil, and the piece B is reversed and
dropped through the tool. Being prevented, however, from
passing quite through, on account of the shoulder just formed, it
is now beaten by the hammer until the head c is formed. The
bolt is then taken out, and the portion c is roughly hammered
into the form of a collar at D. It will now have become cold, and
must be re-heated to finish the head, which is done in the hexa-
$i                        gonal swage E, side after side being presented to the tool by turning

jjl                        the bolt round, and hammering each time.    Finally, it is dropped

into the heading tool once more, as at F, and, after receiving one
or two finishing blows, a cupping tool / is applied to give the
spherical chamfer.

We may now make a Nut for the above bolt Of course, it is
almost unnecessary to state that bolts, nuts, and rivets are now
made entirely by automatic machinery, and these examples, there-

f jf                       fore,  are only intended as an   introduction   to   more  difficult

forging.    A nut can be forged in the form of a ring, and thus

j|li                       dispense with after-drilling.    This is the case we shall consider.

\\                     Fig.   105 illustrates the different operations.    Slightly scarf the

bar A, which is to be bent round to form the nut, and must, there-
fore, have the same width as the latter; for example, a three-
quarter inch nut would require a bar about three-quarters of an
inch by three-eighths of an inch in section. Next heat the end of
the bar and bend round the anvil as at B, nicking it through with
a blunt chisel (as shewn at a in sketch c). Now, put it back in the
fire to get a welding heat; take it out; and, breaking off sharply
at a, lift up the ferrule remaining, on a mandril D, and weld the
two scarfings together; then finish the hexagon in the swage E.
The nut is not yet complete, however. Re-heating, it is cupped
at top and bottom as at F, and the hole is finally made to
exact size by the finishing mandril , which is driven through
the nut into the hole h in the bottom cupping tool. The nut
may now be removed and cooled.

Fig. 106 shews the making of a Holdfast for pipes, or pipe
hook. Two heats are necessary. In the first a bar is taken, as at
A, and is drawn to a s square' point on the further edge of the
anvil as at B, a turn of 90 backward and forward between each